Investigation to simulation of control strategy of parallel hydraulic hybrid vehicles based on backward modeling

Based upon the engine efficiency map and hydraulic pump/motor efficiency curve, a real-time control strategy is proposed for parallel hydraulic hybrid vehicles (PHHV) using the load leveling concept and logic threshold approach to control the torque distribution, various operation modes and the dynamical transitions between the modes for the hybrid power train. In the environment of the backward simulation system model of PHHV developed using MATLAB/Simulink, the control algorithm is designed and tested with the aid of computer simulation. The simulation results demonstrate that the energy control strategy can reasonably switch among various operation modes, optimize the engine operating point and hydraulic pump/motor efficiency, satisfy vehicle dynamic performance and reduce fuel consumption effectively.